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Thin Film Solar Cells: New World Record for Solar Cell Efficiency

21.01.2013

Scientists at Empa, the Swiss Federal Laboratories for Materials Science and Technology, have developed thin film solar cells on flexible polymer foils with a new record efficiency of 20.4% for converting sunlight into electricity. The cells are based on CIGS semiconducting material (copper indium gallium (di)selenide) known for its potential to provide cost-effective solar electricity. The team has succeeded in modifying the properties of the CIGS layer, grown at low temperatures, which absorbs light and contributes to the photo-current in solar cells.

Over the years the laboratory has boosted the photovoltaic conversion efficiency of flexible CIGS solar cells time and again, from 12.8% in 1999 – the group’s first world record – to 14.1% in 2005, 17.6% in 2010 and 18.7% in 2011. What’s more, Empa’s new record efficiency for flexible solar cells now even exceeds the record value of 20.3% for CIGS solar cells on glass substrates – and equals the highest efficiencies for polycrystalline silicon wafer-based solar cells

Thin film, lightweight and flexible high-performance solar modules are attractive for numerous applications such as solar farms, roofs and facades of buildings, automobiles and portable electronics and can be produced using continuous roll-to-roll manufacturing processes that offer further cost reductions compared to standard silicon technologies.

Now it is time for the next step, the scale-up of the technology to cover large areas in a cost-efficient roll-to-roll manufacturing process with an industrial partner. For this purpose, Empa is collaborating with Flisom, a start-up company involved in industrialization of flexible CIGS solar cells.